A typical chuck has a chuck body rotatable about an axis, a plurality of jaws radially displaceable on the body for gripping a workpiece, a chuck drive for rotating the chuck about the axis, and a center point axially shiftable in the body and axially engageable with the workpiece gripped by the jaws. As described in DE 91 13 879 the jaws are moved by a hydraulically powered piston. A piston chamber can be provided to move the center point in the piston in order to actuate the jaws, thereby creating a space-saving double-acting piston configuration.
When crankshafts are produced, the crankshaft workpieces are face-milled at their end faces. Then a center hole is formed in each end face whose function is to allow precise axial centering of the crankshaft for subsequent radial machining. The crankshaft is typically clamped between two center points—one being fixed and the other being axially moveable. Using a hydraulic arrangement for moving the center point makes it very difficult to meet the requirements for environmentally friendly energy-efficient technologies. With this in mind, it becomes necessary to seek new approaches for its axial actuation.